Manufacture of electric circuit components



P. EISLER April 19, 1955 MANUFACTURE OF ELECTRIC CIRCUIT COMPONENTS 8Sheets-Sheet 1 Original Filed Feb. 3, 1944 F/GZ PAULEISLER WM 16% was 9A tturney By" y April 19, 1955 P. EISLER MANUFACTURE OF ELECTRIC CIRCUITCOMPONENTS Original Filed Feb. 3, 1944 8 Sheets-Sheet 2 A ril 19, 1955P. EISLER 2,706,697

MANUFACTURE OF ELECTRIC CIRCUIT COMPONENTS Original Filed Feb. 5, 1944 8Sheets-Sheet S IIIJIIJIII.

Inventor PAUL EISLER iii wmmzw A Home April 19, 1955 P. EISLER 2,706,697

MANUFACTURE OF ELECTRIC CIRCUIT COMPONENTS Original Filed Feb. 3, 1944 8Sheets-Sheet 4 F/GS F/GS

Inventor PAUL EasLaR B Q V/WYAZQM) April 19, 1955 P. EISLER 2,706,697

MANUFACTURE OF ELECTRIC CIRCUIT COMPONENTS Original Filed Feb. :5, 19448 Shets-Sheet s F/ p 1.. I MA 7 [HUGH/0] PAUL EISLER A Horney April 19,1955 P. EISLER 2,706,697

MANUFACTURE OF ELECTRIC CIRCUIT COMPONENTS Original Filed Feb. 3, 1944 8Sheets-Sheet 6 a; f/ 5/6. /3. 7772 mm? 1L W w j llllgn/nr PAUL EISLER flo M 344:

A Home April 19, 1955 p EISLER 2,706,697

MANUFACTURE OF ELECTRIC CIRCUIT COMPONENTS Original Filed Feb. 3, 1944 8Sheets-Sheet 7 F/G/S.

'Hcm'ur PAUL LISLER A tturney United States Patent MANUFACTURE OFELECTRIC CIRCUIT COMPONENTS Divided and this application December 17,1951, Serial No. 261,989

16 Claims. (Cl. 154-95) This invention relates to the manufacture ofelectrical apparatus, and particularly to the production of electric andmagnetic circuits and parts thereof.

A principal purpose of the invention is to facilitate and cheapenquantity production of electric circuit components, such as theresistances, inductances, transformers, tubes and interconnectingnetworks or circuit connections of radio apparatus, the cores andwindings of iron-cored transformers and dynamo electric machines, theconnecting networks of switchboards, the conductors of heatingappliances, and generally of any electrical circuit component which itmay be convenient to manufacture by the methods herein disclosed.

A further purpose of the invention is to facilitate the production ofelectrical circuit components, even though they be not needed in greatquantities, in which a high degree of precision is required in thedimensioning or relative location of conductors such as cannot readilybe obtained by known means.

Yet another object of the invention is the production of surface heatingelements in which the conductor also constitutes or carries anornamentation.

Other objects of the invention will appear from the descriptionfollowing.

Most electrical circuit components essentially comprise metal parts,conducting electric current or magnetic flux, supported upon aninsulating base, or with interposed insulation upon a metal base.

The invention consists in the production of the metal electric andmagnetic conductors in position upon their insulating support by aprocess based on the printing of a representation or pattern of theconductive metal.

The common way of building up an electrical circuit or circuit elementis first to draw metal into wire, that is to say, make a linearconductor, and afterwards to shape this conductor into coils andnetworks. By the application of the methods of the printing art theinvention brings the metal conductor of the circuit component intoexistence in its final form, or in a development of that form upon aplane or cylindrical surface.

A typical instance of the invention comprises the steps of preparing byany of the well-known methods of the printing art, a printing plate forprinting a representation of the metal electric or magnetic conductorsof the circuit component or a part of them; making an imprint by the aidof the printing plate upon a surface thereby differentiating on thatsurface the areas which are required to be conductive from the areaswhich are required to be non-conductive; and from that imprint producingthe conductor by subjecting the printed surface to treatment whichoperates differently on the areas of the surface differentiated by theprinting, thereby changing the diiferentiation into a differentiation ofconductive and non-conductive areas.

The development of the conductor from the imprint is in most caseseffected by methods adapted from the printing art or analogous to themethods of the printing alt, such as etching, bronzing,electro-deposition and the li e.

Where on account of the process of development adopted, or on account ofthe nature of the fabric which is to form the permanent base of theconductor, it is inconvenient to make the imprint or pattern on thepermanent base, it may be made on a temporary base, which must beremovable, and the development process 2,706,697 Patented Apr. 19, 1955process akin to those known in be followed by a transfer the printingart.

The invention is explained hereinafter by a description of theproduction of various circuit components by its aid. This descriptionrefers to the accompanying drawings in which:

Figure 1 is a diagram of connections of a radio receiver.

Figure 2 is a diagram showing the approximate layout of the componentsof this receiver.

Figures 3 and 4 show two part schemes of connections prepared for thepurpose of applying the invention to the manufacture of the circuitconnections of this receiver.

Figure 5 is a cross-section illustrating the making of connectionsbetween one part scheme of connections and another and between thecircuit leads and a component by means of an eyelet;

Figure 6 is a cross-section illustrating the making of connectionsbetween one part scheme of connections and another and between thecircuit leads and a component by means of stitching wire.

Figure 7 is a pattern of flat spirals illustrating the making ofinductance coils according to the invention by printing with theadditional step of folding.

Figure 8 illustrates another way of joining parts of a component.

Figure 9 illustrates a printed pattern of parallel conductors havingmany useful applications.

Figure 10 is a pattern of lines on a principal sheet and a connectorlabel illustrating the making of a helical inductance coil according tothe invention by printing with the additional steps of winding theprincipal sheet and attaching a connector label.

Figure 11 illustrates the making of a transformer core according to theinvention.

Figure 12 is a section of a helical inductance and its label showing howthe label is positioned by embossing.

Figure 13 illustrates a modification of the pattern of parallel lines.

Figures 14 and 15 illustrate the making of an inductance from a patternof rectangles with the additional steps of twisting and winding on adouble core.

Figure 16 is a cross-section of a transformer built by the method of theinvention and Figure 17 illustrates the printing of its core.

Figures 18, 19, and 20 illustrate the application of the invention tothe printing of the conductors of dynamo electric machines.

Figures 21 and 22 illustrate the application of the invention to theprinting of the conductors of a thermionic tube or valve.

The diagram of connections or hook-up shown in Figure 1 forms no part ofthe invention, is substantially known, and therefore will not bedescribed further than is necessary to assist the understanding of thelater figures. It is seen to consist of valves V1, V2 etc., resistancesP1, R1, R2 etc., inductances such as L, capacitances C1, C2, etc., anoutput transformer LS, and a network of conductors by which these othercomponents are connected together. It is the production of theconnecting network that will first be studied.

The radio engineer charged with the manufacture of a radio receiveraccording to Figure 1, must first plan the layout of the severalcomponents, including the connecting network, and produce a layout andwiring plan such as is shown in Figure 2. The design of this layout isagain a matter for the radio engineer with which the present inventionis not primarily concerned; though the radio engineer familiar with thepresent invention will naturally in planning his layout have regard tothe fact that such and such components of it are to be made by themethods of the present invention. The correspondence between Figures 1and 2 is sufiiciently apparent from the references upon the severalparts already mentioned.

It will be noted that the circuit connections shown in Figure 2 involveseveral instances of crossing conductors; for instance, the connectionfrom LS to V3 crosses the connection from R3 to V3. In wiring withpre-formed wires such connections are kept separate by suitabledisposition in three dimensions; Figure 2 is not intended 3 to representsuch disposition; indeed some conductors are displaced to one sidemerely for the sake of clearness.

For the application of the invention to the manufacture of such anetwork it is manifestly convenient for the connections to be disposedin one plane; but if they cannot be so disposed without crossings, itwill be convenient to dispose them in two or three or more planes; somaking the network two or more circuit components which are printedseparately or side by side and afterwards assembled in superposition orother desired relation and connected together where necessary.

In the present instance the whole of the circuit connec tions canconveniently be set out in two planes, and they are shown so set out inFigures 3 and 4. The general resemblance of Figures 3 and 4 to thelayout plan of Figure 2 can be seen at a glance, and the location ofvarious components other than the network itself can readily berecognized. For example, V1, V 2, V3 and V4 in Figures 3 and 4 mark thelocation in the network of the tubes or valves indicated by thosereferences in Figures l and 2. It will be seen that if Figure 4 bedirectly superposed on Figure 2 the valves, or rather valve holders,indicated in the latter figure come in the places to which valveconnections converge in Figure 4. Figure 3 will similarly register withFigure 2 and with Figure 4 if turned face downward. If thecorrespondence of these figures be studied in detail it will be seenthat some con ductors shown in Figure 2 appear in part in Figure 3 andin part in Figure 4; for example, the connection between V2, C9 and R7in Figure 2 is represented by the connection a, b from the position ofV2 in Figure 4, the connection b, c in Figure 3, and the connection 0, ain Figure 4. Provision has to be made for joining these con nectionsinto one conductor in the finished articles; for this reason the partsof it are drawn so that their ends overlap when Figures 3 and 4 aresuperposed back to back; thus the points b and c of Figure 4 overlap andregister with the points b and c of Figure 3.

To make possible the employment of universal tools, as hereinafterdescribed, in the manufacture of various schemes of connections, ofwhich Figures 1 and 2 are only one example, it is convenient to limitthe possible positions of junction points such as b and c. For thisreason, it is of advantage to prepare the drawings of the part schemes,Figures 3 and 4, by the aid of squared tracing paper and to arrange thatevery junction point falls upon an intersection of the lines of thegrid. it would only confuse Figures 3 and 4 to superpose such a gridupon them; two lines of the grid are indicated by the chain lines 21passing through the point e in both Figures 3 and 4.

From the drawings, Figures 3 and 4, printing plates are prepared by anyof the usual methods of the printing art. These printing plates may, forexample, be engravings on metal, or lithographic stones, or they may beprepared by any usual photomechanical process, or they may bephotographic plates. The printing plates so produced may be in relief,in intaglio, or planographic, according to the method of production.

From the two printing plates so produced any desired number of identicalprints of the circuit component may be made.

In one form of the invention, convenient for the instance underconsideration, the prints are made upon a composite material consistingof metal foil upon an insulating backing. The thickness and nature ofthe foil and of the backing depend upon the particular process chosenfor converting the imprint of the circuit component into a circuitcomponent. Metallized or metalcoated paper is one material; it ispreferable to impregnate the paper with antacid-resisting varnish madeof a suitable plastic. Or metal foil may be coated with var nish or witha layer of plastic of the desired thickness. Or a metal coating may beapplied to a pre-formed sheet of insulating material, such as a plastic.Zinc, aluminum, and copper may be named among suitable metals.

For the purpose of the particular example of the invention now underconsideration, the print is made with an acid-resistant ink upon themetal side of such composite material. Except Where the pattern to beprinted is very fine it is an advantage to impart a grain to the metalsurface by use of an etching bath, or by abrasion or otherwise, prior toprinting. The print may be made directly from the printing plate or bythe olT-set method. To ensure a print free from pinholes, the print maybe overprinted, or otherwise reinforced. The print is naturallyidentical with Figures 3 and 4, and those figures equally represent thedrawing from which the printing plate was prepared, and the print madefrom the plate upon the metal surface of a composite sheet.

The part circuit components are next perforated at all the points atwhich junction has to be made between the conductors of the sheetcorresponding with Figure 3 and those on the sheet corresponding withFigure 4, that is to say at all points such as c. The restrictedlocation of such junction points as above described enables all theperforations, whether for these particular components or for any othercircuit components of like area, to be made by a universal punching toolin which pin punches can be inserted at any of a large number ofpositions corresponding with the intersections of the grid employed inpreparing Figures 3 and 4. If there are large areas of metal to beremoved they may be punched out prior to etching, for instancesimultaneously with the perforation, so as to even up the extent ofetching necessary all over the print.

The sheet is then etched in the well-known manner of the printing art,in a bath suited to the particular metal employed, but with thisdifference from the usual etching of a printing process that the metalnot protected by the resistant ink is wholly etched away. To permit ofthis complete etching away without undue undercutting of the rotectedparts it may be convenient, as is commonly done in preparing printingplates, to interrupt the etching and re-coat the surface, for instancewith a fatty ground, which can be made to protect the sides of theetched lines as well as the outer surface. When etching is complete theink may be washed off.

it will be clear that Figures 3 and 4 equally represent the etchedprint, that is to say, they may be regarded as epicting a sheet ofinsulating material coated with metal over the shaded parts only.

The two part circuit components are now superposed back to back andmetallic junctions are made between them at all the perforations. Suchconnections may he made the manner now common in the radio art by meansof eyelets. Figure 5, for example, shows a crosssection of a smallportion of an insulating sheet 22, having conductors 23 on each side of.it produced by printing methods such as that above describcd or thosedescribed hereinafter, and the conductors on one side are joined toconductors on the other side, and to the terminal tags of other circuitcomponents such as the resistance 24, by cycle-ts or hollow rivets 25.Or such connections may be made by w..e stitching, using wire staples,or wires, bent twice at right angles into 3 form as seen at 26 in Figure6, and the terminal wires 27 of a component such as the fixedcapacitance 2'8 of Figure 6 may he used for such stitching. The eyeletsor wires are preferably tinned and soldenpainted, so that the joints maysubsequently be perfected by solderin This operation also may beperformed by a heated universal tool in which soldering bits are set atthe position of the junctions of the circuit component in course ofmanufacture. if desired the metal may be protected and insulated by acoating of varni .1 except over points required to be accessible forpurposes of testing or the making of further connections.

The circuit may be tested by a universal testing appliance which permitsof contacts being set in desired positions on a surface.

if desired, a single printing plate may reproduce the tworepresentations, Figures 3 and 4, side by side, on the same compositesheet. in that case the conductors developed from the print aresuperposed by folding the sheet back upon itself with the conductorsoutward' 'It will be seen that the essence of the partic i 1' method ofproducing circuit components just described is the preparation of aprinting plate, the printing from it of a representation of theconductors of the circuit component, thereby differentiating on theprinted surface the areas which are required to be conductive from thosewhich are required to be non-conductive, and the subjecting of thesurface to an after treatment which opcrates dilferently on thedifferentiated parts and c011 verts the difierentiation into adifi'erentation of conductive and non-conductive areas. The mprint madeis a positive imprint, that is to say, the inscd part represents theconductors of the component; and the imprint is made on metal; and thecomponent is completed by removal of metal from the unprinted areas. Itwill be seen below that it is not essential that the imprint bepositive, nor that the imprint be made on metal, nor that the componentbe developed by removal of metal.

In the particular method just described removal of metal was effected bychemical etching; it could equally well be removed by electrolysis, theprint being made on metal foil upon a conductive backing, say of anothermetal, and the printed surface being made the anode in a bath ofelectrolyte which attacks the foil. This method is appropriate when itis to be followed by transfer of the conductor to a permanent insulatingbase, after which the conductive backing is dissolved or otherwiseremoved. In the case of some metal foils, for example aluminum, it maybe convenient, instead of removing them wholly, to convert them intonon-conductors, a process well known as anodizing, and which alsoconsists essentially in making the metal an anode in a suitableelectrolytic bath.

instead of producing the circuit component from the imprint by removalof metal it may be produced by adding metal. For example, the printingplate may be prepared to print a negative of the circuit component, thatis to say, to cover with ink those parts of the surface which are to benon-conductive. A negative imprint can be made in insulating ink uponmetal foil say zinc foil, on a suitable backing, and additional metal ofa different kind, say copper, can be added to the parts not inked byeiectro-deposition, the printed foil being made the cathode in anelectrolytic bath. Or the printed foil may be sub jected to agalvanizing process by coating it with flux and passing it through abath of molten metal, which must naturally be a metal of low meltingpoint such as Rose metal or a soldering alloy, melting at a temperaturewhich will not harm the insulating backing. These methods, also,appropriately precede transfer, for the metal foil must subsequently beremoved, at least over those areas covered by the ink and therefore notcovered by added metal, and this may readily be done after transfer inan acid bath which attacks the metal of the foil but not the addedmetal.

The printing plate may be a photographic plate or film, in which casethe imprint is made by contact printing or projection upon a sensitizedsurface. For example, a metal plate may be gelatine coated as andprinted from a negative of the circuit component. The coating ishardened where it is exposed to light and elsewhere may be washed away,and the metal so uncovered can be etched away, preferably in stages. Orthe hardened gelatine may be inked, and dusted with metal which isconsolidated as above described. The imprint may be transferred to apermanent base prior to consolidation, and this is necessary if thegelatine could not withstand the consolidation process chosen.

Any of the be followed by the step of transferring the imprint from atemporary to a permanent base, provided due regard be paid to therequirements of that step in the selection of materials.

These various methods by which an imprint of a circuit component isconverted into a circuit component are to be regarded as illustrativeexamples only; to those acquainted with the printing art, from whichmost of the individual steps employed are taken, with some modification,it will be obvious that many other modified operations or modifiedsequences of operations may be adopted according to the nature of thecircuit component that is to be made. A few of these are mentioned belowin connection with the making of particular circuit components.

Reverting to the radio receiver of Figures 1 and 2. there has so farbeen described the production of only one of its circuit components,namely the circuit COW nections, which can be produced by any of themethods above described. To what extent it is convenient to employ theinvention in the making or" other components of the radio receiver is aquestion to be answered on economic grounds. The illustrative examplesnext described show that other components may readily be made by similarmethods, and those examples will assist in indicating how the design ofcomponents may usefully be modified with a view to their beingmanufactured by :t printing process.

The inductance L of the antenna circuit may take the well-known if lessusual form of a fiat spiral, such as in zincography,

processes above described may include or the lines.

one of the spirals 31 of Figure 7. exigencies of drawing the spiral isof a few well spaced turns; the printing methods above described,particularly, for example, the method of printing and etching firstabove described, permits of the making of a spiral of hundreds of turnsspaced apart no more than a few thousandths of an inch. Hence a singlespiral will commonly suffice for the inductance L. The spiral is drawnout carefully, a printing plate is made from the drawing, an imprint ismade on metal foil, on an insulating backing, and the metal notprotected is etched away; or another of the procedures above describedis followed.

if greater inductance is required than can conveniently be obtained in asingle spiral-for example if a winding of a great number of turns isrequired with or without an iron core-the spiral pattern may be repeatedas often as desired. A convenient pattern is that shown in Figure 7,which consists of pairs of spirals 31, 32, joined at their outer ends.The free ends of the spirals form junction points 34, and it will benoted that some of these, but not all, have the same angular position aseach other; for example, no two of the spirals in the second row havetheir free ends in the same position, but each of them has its free endin the same position as has the spiral beneath it in the third row. Thispattern may be printed on metal on an impregnated paper backing whichcan readily be folded. After the print has been metallized in one of theways above described and its surface coated (or left coated) withinsulation, except at the junction points, the sheet is folded about theline 35'35. The junction points become superposed in register and may beconnected by spot-welding by a universal welding tool analogous to thesoldering tool above mentioned. Or they may be joined as explained withreference to Figures 5 and 6. After the junctions have been made theprint is further folded about the lines 36-36, the line 37-37 and thelines 3833. By a small modification in the pattern, junction points maybe made to abut upon one another on folding, as shown in Figure 8, whichis a cross section of several spirals 41 on insulating sheets 42, theinner or outer end of each spiral being folded to abut on the inner orouter end of its neighbor; the spirals are held together by the bolt 43which exerts sufficient pressure to make a metallic connection at thepoints of abutment. If an iron core is to be used the centers of thespirals of Figure 7 are punched out along the dotted lines 39 beforefolding, and the insulation between spirals may also be punched out asindicated by the dotted circles surrounding the spirals.

Figure 9 may be referred to here as illustrating a pattern of parallellinear conductors 51 upon an insulating ground 52, a pattern which mayreadily be produced by the method of the invention and which is thefoundation of several varieties of circuit components. It will be seenthat at each end of the pattern all the lines are joined so thatelectrically they are in parallel. In addition alternate pairs of lines51 are joined further from the edge of the pattern so that if theextreme edges are sheared off the lines will be electrically in series.Again it is to be noted that exigencies of drawing make Figure 9 highlydiagrammatic; in fact the pattern can be of enormously greater length,and be composed of a very great number of closely spaced lines. Figure 9will be further described below. It is mentioned here as completing theillustration of the circuit component shown in Figure 10. In thisFigures 55 and 56 show the two ends of a long strip of flexibleinsulation bearing a pattern of parallel metallic lines, such as isillustrated in Figure 9, but in this case Without any end connectionsbetween This pattern is here used as the basis for making a helicalwinding to serve as an inductance, or as the winding of a transformer orfor like purposes. After printing and development of the metallic linesthe strip is wound upon a former or upon a core such as that shown inFigure ll. It would ordinarily be a very tedious operation to wind awire winding upon a closed core such as Figure 11 depicts, perhapsinvolving threading the bobbin through the core some thousands of times.But when it is remembered that the strip of Figures 9 and 10 may havehundreds of conductors side by side, it will be understood thatthousands of turns of wire may be wound about a core by threading such astrip through it only a few times. However, the winding of the strip onthe core in this manner only leaves the core winding Onaccount of shownas consisting with, say, a thousand separate conductors each encirclingthe core a few times. it remains to join these conductors in series,which involves, say, joining the end of the lowermost conductor in theend 55 of the strip to the uppermost in the end So and so on. This isconveniently done by the aid of a label 57 of transparent insulatingmaterial bearing a pattern of parallel conductors of similar spacing tothe conductors of the strip 55, 56 insulated at their middle parts butbare and solderpainted at their ends. In order that this label may beaccurately applied to the ends 55, 56, as is necessary considering theclose spacing of the conductors, the label is not only printed butembossed, preferably in the printing operation, so that the ends of itsconductors lie in grooves. Figure 12 shows a section of the label 57 andof the end 56 upon the lines XII-Jill of Figure 10, and shows the end ofthe label superposed upon the end of the strip. it will be seen that theembossed parts of the label will fit between the conductors of the stripand thereby cause the conductors of strip and label to be accuratelysuperposed. A soldered joint is mace by heat and pressure. The flaps 58of the label may be coated with adhesive and folded around and madeadherent to the back of the ends 55, 56.

If it is desired to have parallel conductors upon a strip such as thatof Figure 9, or the strip 55, 56 of Figure 10, more closely spaced thanlines can reliably be printed, the spacing of the lines may be increasedto a little more than the width of the lines, and after printing andmetallizing the lines may be varnished with plastic. The strip can thenbe folded about a mid line (59, 59, Figure 10), running lengthwise ofit, so that the conductors of one half of the strip come to lie betweenthose of the other half; this is seen in Figure 13 which is across-section of such a folded strip, 61 being the insulating backing,62 the conductors, and 63 their insulating coating.

Where the invention is applied to the making of the magneto-conductivepart of an electrical circuit component, such as a transformer core, themetal employed for metallization is naturally iron. The invention isespecially of value in the making of cores for radio frequencytransformers for in these it is worth while for the avoidance of eddycurrent losses to divide the iron of the core, not merely intolaminations, but into separate and fine wires. The printing of a patternof parallel iron conductors as shown in Figure 11 upon a ground of thethinnest insulation that will afford the requisite strength and has thedesired electrical properties, and the stamp ing out of the pattern fromthe sheet and of the center from the pattern as indicated by the dottedlines, need no further explanation; nor does the building up of the coreby assembling a great number of such patterns in a pile. Obviously anyusual form of laminated core may be built of printed line patterns inthis way.

Figures 7, l and 12 illustrate different ways in which theelectro-conductive or magneto-conductive part of a circuit componentoriginally printed on a fiat sheet, or maybe on a cylinder, may bedeformed into a three dimensional structure; Figures 14 and 5, showingan alternative way of building a cylindrical coil, for instance a relaywinding, illustrate a third kind of deformation. In this case theprinted pattern consists of a great number of elongated approximatelyrectangular turns one within the other; the middle part of the figure isbroken away to indicate that its length may be large compared with itswidth. When this is metallized the conductor is continuous from end toend. It is formed into an inductive winding by stamping out its middleas indicated by the dotted line and winding it on the two-part core orformer shown in Figure 15, preferably so that its ends becomesuperposed, and then turning one part of the core or former end for end,thereby twisting the ends of the rectangular pattern, and bringing itslong sides into juxtaposition with the current travelling around thecore in the same direction in all of them.

' As already mentioned, where it is intended to use the method of theinvention for the production of a circuit component regard may be had tothat fact in the electrical design of the component. Figure 16 is across-section of a transformer designed to be built by the method ofthis invention. Its windings 61 may be built of superposed spirals, suchas are illustrated in Figure 7, all of the same external diameter butdecreasing in radial depth from the middle outwards. Primary andsecondary windings may be printed together, closely intermingled toelim- Cir 0 t3 inate magnetic leakage. Together the superposed imprintsform an annulus of roughly triangular cross-secrion. Alternatively thewinding may be wound of wire upon a former of Vsection. The core isbuilt from the printed strip 62 shown in Figure 17; it is a slightlytapering strip (the taper is exaggerated in the figure) on which areformed a large number of parallel closely spaced iron lines. This stripis of very thin insulating material. The middle of the strip isreinforced by a narrower tapered strip 63. The composite strip is woundaround the winding 61 and as it is wound it is folded about the edges ofthe reinforcing strip, so that the ends of the iron lines come togetherin the middle of the core as seen in Figure 16. its insulation breaksand crumples permitting the iron lines to overlap radially. The ends ofthe lines are brought into good magnetic contact and so held by the endcheeks 64 and the bolt s5.

The invention is by no means confined to the building of circuitcomponents for radio receivers. The pattern of parallel lines describedwith reference to Figure 9 is a typical pattern for the production ofelectrical resistances, for example for al kinds of heaters. The patternof parallel resistant conductors may be wanted upon some article orfabric to be heated on which it is not convenient to print. in that casethe resistant pattern is produced by printing upon a temporary ground,for instance printing upon foil of resistant metal upon a backing ofwaxy paper, and is transferred to its perma nent backing by a subsequentoperation. The method of printing and etching and subsequent transfer,for example, might well be used to produce a resistant conductor uponcement or plaster of Paris.

A resistant conductor such as indicated in Figure 9 may be formed uponwall-papers, wall and furniture panels, curtains, and other hangings,upholstery fabrics, floor coverings, clothing and bed-clothing, and thelike for the purpose of making electric heaters or rather warmers ofthem. Such a conductor, though of small thickness, will carry asubstantial current because its fiat form promotes loss of heat byradiation and conduction. The conductor will be insulated and protectedby a covering, for instance of a varnish or plastic on which powderedmetal oxide may be dusted to increase radiation; in the case of aluminumthe conductor is preferably covered by oxidation for the same reasons.

When used on ordinarily ornamental fabrics such as wallpapers, thepattern of Figure 9 may be made to provide or contribute to theornamentation by a double printing process. There is first produced apattern of parallel lines of say, aluminum, copper, zinc, iron ornickel. Upon this any ornamental design 53 is printed in an insulatingink. The sheet is then made the cathode in an electrolytic bath by whichcopper is deposited on the metal lines except where covered by ink. Thefinal product is, as before, a sheet with a pattern of parallel lines ofwhich those parts within the design are of higher resistance than theremainder. Alternatively, the over-printed sheet may be anodized tobring about reduction in the cross-section of the unprotected parts.

However, the second pattern may be superposed merely for its appearancewithout any thought of making the pattern rather than the non-patternedpart the source of heat, or vice versa. In this case it may be desiredto render the pattern of parallel lines inconspicuous to the eye, bysuitable dyeing of the base, or of the oxidecoated or otherwiseinsulated conductor. For such overprinting a pattern of parallel linesof aluminum may be used with advantage, and the sheet subjected to ananodizing process and dyeing process by which eifects of some beauty maybe produced. By the use of dyes which change color at a temperatureabove atmospheric and below that which the conductor, or a part of it,reaches when carrying current, a visual indication may be given when theheat is on. Such substances are well known in the art.

A class of printed patterns deserving mention is the patterns forwinding the toothed cores of dynamo-electric machines. In one form shownin Figure 18, the pattern is mainly a star, in which each ray is a groupof parallel conductors, 71 representing the conductors of one slot; theinner and if desired the outer ends of the rays are prolonged at anangle to their length to form connections preferably of the form ofinvolutes of a circle; the insulating material between the groups ofslot conductors is removed as indicated by the doubled lines, so thatthe slot conductors may be folded through a right angle to enter theslots. Or the slot conductors may appear in the pattern as parallelgroups of parallel lines 73 (as seen in Figure 19) upon an insulatingsheet which is to be wrapped around the slotted core, openings beingpunched between the slot conductors, as indicated by the dottedrectangles, for the passage of the teeth. The end connections may bebrought into their proper relative position by folding of the insulatingsheet. For example, the pattern may consist of two rows of groups ofparallel lines 73, 74, those of one row being joined to those of theother by other parallel lines 75 at an inclination to the groups, whilethe outer ends 76 of the group are prolonged at the same inclination. Byfolding this pattern about a line 77 at right angles to and midwaybetween the groups, the latter are superposed in the same slots or madeto lie side by side in neighboring slots, while the inclined lines 75and 76 become end connections of V form. The rectangular openingspunched in the insulating sheet between the groups, as indicated bydotted lines, encircle the teeth when the winding is placed on the core.

The invention is even more readily applicable to dynamo-electricmachines employing an armature of discform or consisting of a pluralityof discs, as in some types of multipole alternator and inductoralternator. One such disc is shown in Figure 20. The conductor 81 hasits radial turns spaced a pole pitch apart, or in the ease of theinductor a tooth pitch apart. The ground upon which the print is madeand the metal built up may be stamped out as indicated by the dottedline 82.

An example of an electrical circuit component in the production of whicha process including the step of transfer is desirable, is the electrodesof a thermionic tube or valve. Figure 21 shows the pattern of theelectrodes for a double triode, with the exception of the cathode. Thereare two grids 84 and two anodes 85. A negative of this pattern may beprinted in insulating ink on metal foil, and another metal may bedeposited electrolytically on the bare lines of the foil. The imprint isthen transferred to a permanent support of glass, which initially is aplane cross 86 as shown in Figure 22 with apertures 87 in it in positioncorresponding to the position of the elements of the grids in Figure 21.The foil which formed the temporary base is then removed. The support 86is heated and (the print being on the upper face) its four limbs arefolded downward through a right angle about the lines 88; then they arefolded outward about the lines 89, and upward about the lines 91. Theassembly is mounted on a glass stem around the cathode; connections aremade from the grids and anodes to wires sealed through the stem, and thewhole is then sealed into a bulb which is evacuated in the usual manner.

This application is a division of my application Serial No. 11,798,filed February 27, 1948, now Patent No. 2,587,568, itself a division ofmy application Serial No. 520,991, filed February 3, 1944, now PatentNo. 2,441,960, dated May 25, 1948.

I claim:

1. A method of manufacturing a component of electric and magneticcircuit systems involving a conductive pathway pattern of such weakmechanical structure that it is incapable of self-maintaining itsconfiguration and backed with an insulation support, said methodcomprising the steps of providing a composite sheet material in form ofan electrically conductive foil backed with a supporting layer, the saidbacking constituting a temporary support for the foil, printing arepresentation of the pathway pattern on said foil, removing theportions of the foil other than those forming part of said pathwaypattern, placing the pattern forming portions of the foil upon aninsulation support, the said support constituting a permanent supportfor the foil, and removing the backing constituting said temporarysupport whereby the pathway pattern formed on the temporary support istransferred to the permanent support.

2. A method of manufacturing the conductive metal portions of electricaland magnetic circuits and circuit components in position upon theirinsulating supports as claimed in claim 1 wherein said backing is a thinconductive material and removed at least over the area not covered bythe imprint after the pattern is transferred to its insulating support.

3. A method of manufacturing the conductive metal portions of electricaland magnetic circuits and circuit 10 components in position upon theirinsulating supports as claimed in claim 1 wherein the insulating supportto which the metal pattern is transferred has at least one apertureacross which said pattern extends.

4. A method of manufacturing the conductive metal portions of electricand magnetic circuits of the kind including a conductive pathway patternupon an insulation backing comprising the steps of printing a negativerepresentation of the desired pathway pattern upon the metal surface ofa sheet of foil clad insulation, thereupon depositing dissimilar metalupon the unprinted surfaces of the foil, and finally removing the foilfrom the imprinted areas whereby an insulation backed metallic pathwaypattern is formed.

5. In a method of manufacturing the conductive metal portions ofelectric and magnetic circuits of the kind including a conductivepathway pattern upon an insulation backing, the steps of printing anegative representation of the desired pathway pattern upon a sheet ofmetal foil, thereupon depositing metal upon an unprinted surface portionof the foil, and then transferring the metal foil to an insulatingsupport.

6. A method of manufacturing the conductive metal portions of electricand magnetic circuits of the kind including a conductive pathway patternupon an insulation backing comprising the steps of printing a negativerepresentation of the desired pathway pattern upon the foil surface of acomposite sheet of foil and a supporting metal, the said metalconstituting a temporary support for the foil, thereupon depositingmetal upon the unprinted surface portions of the foil, removing theprinted foil portions, transferring the pathway pattern thus formed to apermanent insulating support, the metal support being thereafter removedat least over the areas not covered by the deposited metal.

7. A method of manufacturing the conductive metal portions of electricand magnetic circuits of the kind including a conductive pathway patternupon an insulation backing comprising the steps of printing a positiverepresentation of the desired pathway pattern in etch resist ink uponthe foil surface of a composite sheet of foil and supporting conductivematerial, the said conductive material constituting a temporary supportfor the foil, thereupon etching away the unprinted areas of the foil andtransferring the resultant pathway pattern to a permanent insulationsupport.

8. A method of manufacturing the conductive metal portions of electricaland magnetic circuits and circuit components in position upon theirinsulating supports as claimed in claim 7 wherein a positiverepresentation of the conductive pattern is printed upon a metal foilprovided with a thin conductive backing which is made an anode in anelectrolytic bath, the metal foil being anodized throughout itsthickness on the areas not covered by the imprint and the conductivebacking is removed at least over the areas not covered by the imprint.

9. A method of manufacturing the conductive metal portions of electricand magnetic circuits of the kind including a conductive pathway patternupon an insulation backing comprising the steps of printing a positiverepresentation of the desired pathway pattern in etch resist ink uponthe foil surface of a composite sheet of foil and a supporting metal,the said metal constituting a temporary support for the foil, thereuponetching away the unprinted areas of the foil, transferring the pathwaypattern thus formed to a permanent insulation support, and removing saidmetal support at least over the areas not covered by the foil metal.

10. A method of manufacturing a component of electric and magneticcircuit systems involving an insulation backed conductive pathwaypattern, which comprises providing insulation backed foil, then printinga negative representation of the pattern upon said foil, depositing alayer of metal dissimilar to the metal of said foil upon all exposedparts of said foil, then removing said representation from the foil, andfinally removing all parts of the foil exposed by said removal of therepresentation by chemical action attacking the metal of said foil butnot said deposited dissimilar metal whereby said pathway pattern isformed.

11. The method of claim 10 wherein the negative representation of thepattern is produced by letterpress printing.

12. The method of claim 10 wherein the negative representation of thepattern is produced by offset printing.

13. The method of claim 10 wherein the negative representation of thepattern is produced by photomechanical' means. i

14. A method of manufacturing a component of electric and magneticcircuit systems involving an insulation backed conductive pathwaypattern, which comprises providing insulation backed foil, then printinga negative representation of the pattern upon said foil with a resistmedium, then depositing by electrodeposition a layer of a metaldissimilar to the metal of said foil upon all exposed parts of saidfoil, then removing the resist medium, and finally etching away allparts or said foil exposed by the removal of the medium in a bathattacking the metal of said foil but not said dissimilar metal wherebysaid pathway pattern is formed.

15. A method of manufacturing a component of electric and magneticcircuit systems involving a backed conductive pathway pattern whichcomprises providing on a backing a foil in form of a metallic layer,producing a negative representation of the pattern on said layer,

then depositing a metal dissimilar to the metal in said layer upon allexposed parts of said layer, and finally removing by chemical actionattacking the metal in said metallic layer but not said dissimilar metalall parts of the metallic layer other than those upon which saiddissimilar metal is deposited whereby said desired pathway pattern isformed.

16. A method of manufacturing a component of electric and magneticcircuit systems involving a backed eonductive pathway pattern whichcomprises providing on a backing a foil in form of a metallic layer,printing a negative representation of the pattern on said'layer with aresist medium, then depositing a metal dissimilar to the metal in saidlayer upon all exposed parts of said layer, then removing the resistmedium, and finally etching away all parts of said metallic layerexposed by the removal of the medium in a bath attacking the metal insaid layer but not said dissimilar metal all parts of the metallic layerother than those upon which said dissimilar metal is deposited wherebysaid pathway pattern is formed.

References Cited in the tile of this patent UNITED STATES PATENTS

5. IN A METHOD OF MANUFACTURING THE CONDUCTIVE METAL PORTIONS OFELECTRIC AND MAGNETIC CIRCUITS OF THE KIND INCLUDING A CONDUCTIVEPATHWAY PATTERN UPON AN INSULATION BACKING, THE STEPS OF PRINTING ANEGATIVE REPRESENTATION OF THE DESIRED PATHWAY PATTERN UPON A SHEET OFMETAL FOIL, THEREUPON DEPOSITING METAL UPON AN UNPRINTED SURFACE PORTIONOF THE FOIL, AND THEN TRANSFERRING THE METAL FOIL TO AN INSULATINGSUPPORT.